issues: 258913450
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| 258913450 | MDU6SXNzdWUyNTg5MTM0NTA= | 1581 | Projection issue with plot.imshow and cartopy projection | 14314623 | closed | 0 | 4 | 2017-09-19T18:10:06Z | 2019-03-07T22:09:41Z | 2019-03-07T22:09:41Z | CONTRIBUTOR | I am experiencing some trouble when using cartopy transformations in the plot module. I am concerned about plotting speed (plotting very high resolution maps of ocean model output takes forever). According to #657 I tried to use plot.imshow but I am getting unexpected results for the map projection. The longitude wrapping does not seem to work and as seen by the mismatch between the ocean mask data and the coastline in the example below, the projection seems to be inaccurate. This seems to be related to the cartopy module (see the last plot which was done 'outside' of xarray). My question is twofold, I guess 1) Is there is any other 'high speed' alternative to plot high resolution maps. 2) Since this error might not appear as drastically in all mapping scenarios, should plot.imshow display a warning, when invoked with a transformation argument, or even an error? ```python import xarray as xr %matplotlib inline import numpy as np import cartopy.crs as ccrs import cartopy.feature as cfeature import matplotlib.pyplot as plt ds = xr.open_dataset('ocean_mask.nc') plt.figure() ax_i = plt.gca(projection=ccrs.Robinson()) ds.wet.plot.imshow(x='lonh',y='lath',ax=ax_i,transform=ccrs.PlateCarree()) ax_i.coastlines() plt.title('imshow') plt.figure() ax_p = plt.gca(projection=ccrs.Robinson()) ds.wet.plot(x='lonh',y='lath',ax=ax_p,transform=ccrs.PlateCarree()) ax_p.coastlines() plt.title('standard plot') plt.figure() ax = plt.gca(projection=ccrs.Robinson()) ax.imshow(ds.wet.data, transform=ccrs.PlateCarree(), extent=[ds.lonh.min().data, ds.lonh.max().data,ds.lath.min().data, ds.lath.max().data]) ax.coastlines() plt.title('cartopy imshow') ```
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completed | 13221727 | issue |
